Some waste treatment plants employ electron beam technology for irradiating sewage for sterilization purposes. In a typical application, the sewage is caused to flow over a waterfall and the falling curtain of sewage is irradiated by an electron beam emitted by an electron beam generator. In order to ensure thorough sterilization, extremely large electron beam generators must be employed to penetrate through the falling curtain, typically in the range of 1 to 10 million eV. Other large systems have been employed for irradiating fluids such as water flowing through a piping system. In such systems, the fluid is irradiated while flowing through the piping system.
The present invention is directed to a fluid sterilization apparatus which does not require a large electron beam generator. The fluid sterilization apparatus includes a sterilization chamber having a cavity therein. A nozzle is included for receiving pressurized fluid and directing a spray of the fluid into the cavity. An electron beam generator having an exit window is mounted to the sterilization chamber for directing a beam of electrons through the exit window and into the cavity of the sterilization chamber to irradiate the spray of fluid. The nozzle is configured to direct the spray of fluid substantially parallel and proximate to the exit window.
In preferred embodiments, the fluid is pumped by a pump and particles in the fluid are filtered from the fluid by a filter. The nozzle directs a thin, flat film of fluid into the sterilization chamber. In one embodiment, the film of fluid is 0.004 to 0.005 inches thick. The cavity of the sterilization chamber includes an outlet through which the sterilized fluid is removed. In one embodiment, the cavity of the sterilization chamber includes a recycling passage for directing a portion of the spray of fluid back for further irradiation. In this embodiment, a wall between the cavity outlet and the recycling passage directs any fluid from the spray of fluid unable to pass over the wall into the recycling passage.
The present invention is also directed to a fluid sterilization apparatus including a container for containing a supply of fluid. A wheel system having circumferential surfaces is rotatably mounted within the container. The wheel system is configured for extending a portion of the wheel system above the supply of fluid with rotation of the wheel system drawing a film of fluid upwardly out of the supply of fluid on the circumferential surfaces. A doctoring member is positioned for controlling the thickness of the film of fluid on the circumferential surfaces of the wheel system. An electron beam generator is positioned for irradiating the film of fluid with a beam of electrons to sterilize the fluid. A fluid removal member is positioned for removing sterilized fluid from the wheel system.
In preferred embodiments, the wheel system includes a first wheel rotatably mounted within the container for drawing the film of fluid from the supply of fluid. In one embodiment, the wheel system further includes a second wheel rotatably contacting the first wheel for receiving fluid from the first wheel to be irradiated by the electron beam generator.
The present invention fluid sterilization apparatus can have a sterilization region and an electron beam generator that are both compact in size. Consequently, the present invention can be made relatively inexpensively in comparison to the large systems in the prior art. When in a compact size, the present invention apparatus is small enough to be easily installed within both new or existing systems or devices requiring fluid sterilization, and in addition, can also be a portable unit.